1. Field of the Invention
The present invention relates to occupant protection apparatuses and occupant protection methods, particularly relates to an occupant protection apparatus and an occupant protection method that have an airbag in which a plurality of chambers can be formed with a single inflator and protect an occupant from a shock of a side impact on a vehicle sidewall by deploying the airbag between a vehicle sidewall and the occupant.
2. Description of the Related Art
An occupant protection apparatus usually have an airbag in which a single chamber is formed with a single inflator and protects an occupant from a shock of a side impact on a vehicle sidewall by deploying the airbag between a vehicle sidewall and the occupant.
As for the enhancement of occupant safety against a side impact by securing a space between the vehicle sidewall and the occupant, since the vehicle sidewall shifts towards an occupant compartment in the vehicle width direction upon a side impact, the airbag is deployed between the vehicle sidewall and the occupant so as to prevent the vehicle sidewall from contacting with the occupant.
Such an occupant protection apparatus having an airbag in which a single chamber is formed with a single inflator can secure a space between the vehicle sidewall and the occupant by, for example, increasing the thickness of the airbag in the vehicle width direction, whereby occupant safety against a side impact can be enhanced.
However, if the thickness of the airbag is increased in the vehicle width direction, the airbag may hit a component such as a door arm rest disposed in the space between the vehicle sidewall and the occupant upon the deployment of the airbag. Therefore, the airbag cannot be reliably deployed between the vehicle sidewall and the occupant should be addressed.
For this problem, the airbag is less likely to hit the component in the space if the thickness of the airbag in the vehicle width direction is decreased. However, a space cannot be secured between the vehicle sidewall and the occupant.
As a countermeasure for reliably deploying the airbag between the vehicle sidewall and the occupant and securing the space between the vehicle sidewall and the occupant, a plurality of side airbag apparatuses could be used, for example.
However, if a plurality of side airbags apparatuses is used, an additional component such as a control unit is required to control the timing of deploying each airbag, whereby the entire configuration becomes complicated.
The addition of the component such as a control unit also leads to cost increase. Moreover, when a plurality of airbag apparatuses is used, the airbags thereof may interfere with each other.
Recently, therefore, in order to achieve an occupant protection apparatus with a simple configuration, there have been needs to an occupant protection apparatus that has an airbag in which a plurality of chambers can be formed with a single inflator and secures a space between an occupant and a vehicle sidewall by reliably deploying the chambers.
In order to achieve an occupant protection apparatus with a simple configuration, for example, Japanese Unexamined Patent Application Publication (JP-A) No. 2008-201172 discloses a side airbag apparatus that has a high-pressure bag and a low pressure bag that are deployed by a single inflator. When the bags deployed, the high-pressure bag is deployed first, and then the low pressure bag is deployed.
In addition, JP-A No. 2011-001051 discloses a side airbag apparatus that has an upper chamber configured to be deployed towards above an arm rest and a lower chamber configured to be deployed towards below the arm rest.
Since the side airbag apparatus according to JP-A No. 2008-201172 deploys the high-pressure bag and the low-pressure bag with the single inflator and protects a chest region of the occupant by the low-pressure bag, the high-pressure bag may hit the arm rest. Therefore, the side airbag apparatus according to JP-A No. 2008-201172 should be improved to reliably deploy the high-pressure bag.
In addition, while the side airbag apparatus according to JP-A No. 2011-001051 deploys the upper and lower chambers such that they do not hit the arm rest, the chambers do not protect the chest region of the occupant.
Accordingly, the side airbag apparatus according to JP-A No. 2011-001051 presses a shoulder region and a buttock region of the occupant using the upper and lower chambers. Since the side airbag apparatus according to JP-A No. 2011-001051 do not press a chest region of the occupant, a chest injury criterion may become higher.
Thus, since the side airbag apparatus according to JP-A No. 2011-001051 does not press a shoulder region and a buttock region of the occupant evenly using the upper and lower chambers, and thus a chest injury criterion may become higher as described above, a countermeasure should be taken to reduce the chest injury criterion.